This invention relates to apparatus for conditioning the hearing of a patient in order to remedy speech problems.
U.S. Pat. No. 3,043,913, issued July 10, 1962 to Tomatis and U.S. Pat. No. 3,101,390 issued Aug. 20, 1963 to Maille disclose systems in which audio frequency signals derived from a patient's voice or another source are passed through two parallel filter channels to an output stage in the form of earphones. Each channel has a characteristic frequency response curve which can be adjusted manually as required. Typically, one channel has a frequency response curve representing the state of rest which is most desirable for the ear, this state of rest being obtained by suppressing high frequency components. The other channel has a frequency response curve in which low frequencies are suppressed. A signal level detector establishes whether the incoming signal is above or below an adjustable predetermined threshold level and a gating means is operable to pass the audio frequency signals through the one channel to the output stage if the threshold is not met and to pass the audio frequency signals through the other channel to the output stage if the threshold is exceeded.
Both patents describe beneficial effects which accrue from using this technique. Essentially, the patient's hearing is conditioned or trained by the use of the two different auditing states and this results in the improvement of many speech problems. This technique has now become well established as a practical tool of speech therapy.
Also recorded in the prior art, for example, U.S. Pat. No. 4,021,611 which issued on May 3, 1977 to Tomatis, is the use of electromechanical vibrators in audio conditioning apparatus. Such vibrators have long been known to assist a patient to hear by conducting vibration through the patient's skull and U.S. Pat. No. 1,969,559 which issued on Aug. 7, 1934 to Kelly discloses the combination of such "bone conduction" with the "air conduction" provided by an earphone.
Theoretical considerations upon which the present invention is based are discussed below.
By comparison to hearing which remains a passive act, listening is defined as an act in which volition plays a part. Listening means wanting to hear or apply oneself. It means placing the auditory apparatus into its maximum adaptive state to capture that which one wants to receive. It is essentially a matter of passing from sensation to perception.
In the most literal and figurative sense of the term it means to "turn one's ear". In order to accomplish this it is necessary to prepare the full complement of accessories which are annexed to the sensitive/sensory organ for the act: i.e. the cochleo-vestibular device, the musculature of the middle ear and the musculature of the outer ear. It is also necessary to organize a whole neurological structure depending on this dynamic function we call listening.
To do this implies:
(1) that the labyrinth, or the complete cochleo-vestibular area be voluntarily prepared
(2) that this "precursory act" which precedes actual hearing be established in the following manner:
(a) by the tension of the hammer muscle (middle ear) which must adapt itself to the tension of the stirrup muscle which controls the action of the labyrinth (inner ear). And so, there is precession, i.e. a precursory act, of the stirrup tension with respect to the ensemble of elements that govern the function of the middle ear: hammer muscles, the muscles of the Eustachian tube, interplay of internal air pressures PA1 (b) by calling into play the entire nervous system so that the whole neurological tree i.e. medullar, pontic, cerebellum and extrapyramidal cortical areas might be available for this voluntary act carried out by the motor pyramidal "pathway" ("track"). PA1 the muscular tension of the body-static or stationary position PA1 dynamic (interaction) PA1 the relative position of the limbs and their segments
Now, through this neurological interplay and through it alone, the cochleo-vestibular labyrinth governs
or, in other words, all posture and gesture.
Actually, the labyrinth conducts the functional and structural organization of the nervous system so that the act of speaking unfolds as a consequence of listening.
On the other hand, it is the role of the nervous system to cybernetically organize the ear's response so that it turns, adapts, prepares to listen or to put itself in a provisional state of readiness to capture, or in a state of cochleo-vestibular precession. The vestibular function is activated through bone conduction which, must precede air conduction or else the labyrinth will not be ready to hear.